Gaskets essentially are used to seal and prevent leakage between two parts. Exhaust manifold gaskets for internal combustion engines seal the gap between the cylinder head and the exhaust manifold. Sealing the gap, however, can be difficult because the head, manifold and gasket all move due to pressure and temperature fluctuations, which results in the gasket being subjected to constant pressure changes. There are also problems due to thermal expansion and thermal contraction, which occurs when the temperatures varies in the cylinder head base. There are also multiple openings in the head and the manifold for exhaust gases and bolts holes. The areas around these openings are known to be put under additional stresses and leakage is common.
Traditionally, multi-layered or single-layered embossed metal provides poor adaptability and limited insulative properties. Thermal motion, resulting from hot exhaust gases, increasing combustion pressure and steep thermal swings, and sheer stresses are created in this area and the multi or single layered embossed metals become over compressed and do not adequately stop the leakage. The same can be said when graphite faced or a steel grommet is used. The thermal motion eventually causes poor recovery and burn out from the joint movement between the head and the manifold.
In view of the foregoing disadvantages of the prior art, it would be advantageous for a gasket to be able to prevent or resist thermal motion to the extent that it negatively affects performance of the gasket. More specifically, it would be advantageous for a gasket to provide a soft and conformable surface to seal imperfections and surface irregularities, and also to withstand high temperatures and still provide adequate recovery.